ADCs (analog-to-digital converters) frequently require calibration. An approach records the differential programmable current through a DAC to compensate for the comparator's output voltage offset at power-on. This recorded current value is then used to calibrate the comparator as needed. As time elapses, however, temperature and/or voltage variation can cause the threshold voltage of transistors in the ADC to change and the output voltage offset to drift, resulting in inaccurate calibration.
Like reference symbols in the various drawings indicate like elements.